This project involves the investigation of the coordination environments around transition metal ions incorporated in oxymethylene-linked poly(ethylene oxide), OPEO, and poly[bis((methoxyethoxy)ethoxy)phosphazene], MEEP, using EXAFS spectroscopy. Both polymers exhibit ionic conductivity when mixed with various inorganic salts. They have the advantage of being completely amorphous at room temperature, an important property for high ionic conductivities. Little is known about the coordination environment around the metal or counter ions in the polymer salt complexes. We have systematically studied the ionic conductivity, composition, and ion coordination environment in the polymer electrolyte composed of CuCl2 dissolved in OPEO. The objective of this work is to determine the extent ion pairing occurs and how it effects the ion conductivity. The experimental strategy involved the preparation of a series of polymer electrolytes of varying CuCl2 concentration in OPEO and then correlating the resulting conductivities to the copper coordination environment. We have found that both chloride ion and oxygen are present in the copper coordination sphere and that the degree of chloride ion coordination does affect the conductivity by reducing the number of free ions. In addition, the fact that Tg (glass transition temperature) varies in a similar manner as the Cl/O coordination ratio suggests that the chloride ions are in effect cross-linking the polymer chains which increases Tg. The increase in Tg indicates a reduction in polymer motion which also contributes to the decrease in the ion conductivity. This work has been published in RChemistry of MaterialsS(Vol. 6, 1994, 1912). Presently, we are finishing work on the OPEO-CuBr2 system in which we have collected both Cu and Br EXAFS data. In the latest experimental run, we collected data on the MEEP-CuBr2 polymer electrolyte system. It will be interesting to compare the CuBr2 coordination environments in the comb branched MEEP polymer system to the linear OPEO polymer system.